Method for preparing sizing agent

Abstract

The invention relates to the field of papermaking. In particular, the invention relates to a method for preparing a sizing agent. The method comprises the following steps: (1) pre-adding a first part of TEA of total TEA into an HEEL-containing reaction system to obtain an HEEL-containing reaction system in which the TEA is pre-added; and (2) adding the remaining second part of TEA of the total TEA and FACl into the HEEL-containing reaction system in which the TEA is pre-added, and carrying out a reaction, wherein the weight percentage of the first part in the total TEA is not greater than 90% of the weight percentage of the total TEA. According to the method, the viscosity of a reaction system can be reduced, and / or toluene-free operation can be realized.

Description

Technical Field

[0001] The present invention relates to the field of papermaking. In particular, the present invention relates to a method for preparing a sizing agent. The method of the present invention can reduce the viscosity of the reaction system and / or achieve toluene-free operation. Background Art

[0002] Paper is formed by the interwinding of materials containing plant cellulose. Plant cellulose has hydroxyl groups, which impart a certain degree of hydrophilicity to the paper. Plant cellulose also interwinds to form a pore structure, and the pore structure has capillary action, which imparts a certain degree of fluid (such as water, oil, ink, fruit juice, etc.) permeability to the paper. Therefore, the paper surface usually needs to be treated to improve its performance. In the papermaking process, the paper surface can be treated by applying a sizing agent. According to different pH values, sizing agents can be divided into acidic sizing agents, neutral sizing agents and alkaline sizing agents. In recent years, medium and alkaline sizing papermaking has become increasingly popular in the papermaking industry.

[0003] A commonly used neutral sizing agent is Alkyl Ketene Dimer (AKD for short), which has a history of application for more than 50 years. AKD is a waxy solid at room temperature. AKD can be used both as an internal sizing agent and as a surface sizing agent. AKD is usually represented by the following structure:

[0004] Where each R a 、R b 、R c and R d group, when it appears each time, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl group. It has been found that each R a 、R b 、R c and R d group in the above-mentioned ketene dimer can be not only a saturated hydrocarbyl group, but also an unsaturated hydrocarbyl group (such as an alkenyl group derived from oleic acid). By convention, the ketene dimer having an unsaturated hydrocarbyl group is still called AKD (Alkyl Ketene Dimer).

[0005] The four-membered lactone ring in the AKD molecule can react with the hydroxyl groups on cellulose to form an ester bond, thereby being located on the cellulose. The hydrophobic long-chain groups (i.e., one or more of R a 、R b 、R c and R d ) in the AKD molecule produce a hydrophobic effect on the fiber surface and cover part of the pore structure, thereby imparting hydrophobicity and anti-permeability to the paper. The reaction schematic diagram of AKD and cellulose is shown as follows:

[0006]

[0007] A typical method for preparing AKD includes the step of adding fatty acid chlorides (FACl) and triethylamine (TEA) to a reactor. During the above preparation process, as the by-product triethylamine hydrochloride (TEA·HCl) is formed, the viscosity in the reaction increases, thus causing a series of problems such as difficult stirring, increased energy consumption, and poor heat dissipation. In many cases, industrially, an inert solvent such as toluene is often added to mitigate the adverse effects of high viscosity. With the improvement of environmental awareness, further requirements for reducing the amount of toluene used have also been put forward.

[0008] A known method for reducing viscosity is to put the residue of the sizing agent produced in an earlier batch (also called HEEL, which includes AKD and TEA·HCl, and optionally unreacted TEA) into the production of the next batch. The HEEL is beneficial to reducing the viscosity of the system in this batch, but still cannot completely eliminate the use of toluene.

[0009] Currently, there is still a continuous demand in the art for methods for preparing sizing agents (especially AKD) that can achieve viscosity reduction and methods for preparation without toluene. Summary of the Invention

[0010] The preparation method of AKD is well-known in the art. For example, AKD is usually produced from carboxylic acid substances through three steps: acylation, dehydrochlorination, and dimerization. An exemplary synthesis process of AKD is shown as follows.

[0011]

[0012] In the AKD shown in structural formula (IV),

[0013] R a The group, in each of its occurrences, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbon group;

[0014] R b The group, in each of its occurrences, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbon group;

[0015] R c The group, in each of its occurrences, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbon group; and,

[0016] Rd The group, in each occurrence thereof, is independently selected from: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl group.

[0017] For any one of R a , R b , R c or R d , the C1-C 30 hydrocarbyl group is preferably a C 10 -C 20 hydrocarbyl group, more preferably a C 13 -C 17 hydrocarbyl group, such as C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 11 , C 12 , C 13 , C 14 , C 15 , C 16 , C 17 , C 18 , C 19 , C 20 , C 21 , C 22 , C 23 , C 24 , C 25 , C 26 , C 27 , C 28 , C 29 , C 30 hydrocarbyl group. For any one of R a , R b , R c or R d , the hydrocarbyl group may be an alkyl group, an alkenyl group, or an alkynyl group; preferably an alkyl group.

[0018] In any one of Structural Formulas I, II, and / or III, the R' group, in each occurrence thereof, is independently selected from: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl group; and / or

[0019] the R'' group, in each occurrence thereof, is independently selected from: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl group.

[0020] For any one of R' or R'', the C1-C 30 hydrocarbyl group is preferably a C 10 -C 20 hydrocarbyl group, more preferably a C 13 -C 17Hydrocarbyl, such as C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 、C 11 、C 12 、C 13 、C 14 、C 15 、C 16 、C 17 、C 18 、C 19 、C 20 、C 21 、C 22 、C 23 、C 24 、C 25 、C 26 、C 27 、C 28 、C 29 、C 30 hydrocarbyl. For either R' or R", said hydrocarbyl may be alkyl, alkenyl, or alkynyl; preferably alkyl.

[0021] The enone of formula (III-1) is synthesized by the same procedure as the enone of formula (III-2) . The R a group is independently selected from, in each occurrence thereof: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl; The R b group is independently selected from, in each occurrence thereof: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl; The R c group is independently selected from, in each occurrence thereof: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl; and, The R d group is independently selected from, in each occurrence thereof: hydrogen; optionally substituted, straight-chain or branched C1-C 30 hydrocarbyl. For any one of R a , R b , R c or R d , said C1-C 30 hydrocarbyl is preferably C 10 -C 20 hydrocarbyl, more preferably C 13 -C 17 hydrocarbyl, such as C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 、C 11 、C 12 、C 13 、C 14 、C 15 、C16 , C 17 , C 18 , C 19 , C 20 , C 21 , C 22 , C 23 , C 24 , C 25 , C 26 , C 27 , C 28 , C 29 , C 30 hydrocarbyl. For any one of R a , R b , R c or R d , the hydrocarbyl may be an alkyl group, an alkenyl group, or an alkynyl group; preferably an alkyl group.

[0022] In the acylation step, (a) PCl3, (b) SOCl2, and (c) COCl2 + DMF are three commonly used acylation means. The means (c) using COCl2 and DMF is the most commonly used acylation means at present, in which phosgene (COCl2) is used as an acylating agent, and dimethylformamide (DMF) is used as a catalyst.

[0023] In the dehydrochlorination step, for the purpose of cost saving, triethylamine hydrochloride (N(CH2CH3)3·HCl) is usually regenerated into triethylamine and recycled.

[0024] In the above reaction 2, the raw material of formula (II) is usually referred to as fatty acid chlorides (FACl for short), which undergoes dehydrochlorination under the action of triethylamine (TEA for short). Accordingly, for the purpose of description only, the raw material of formula (I) in the above reaction 1 is referred to as fatty acid (FA for short) herein, whether it is saturated or unsaturated.

[0025] Therefore, a typical step of the AKD preparation method involves contacting TEA and FACl for reaction, and its reaction formula can also be written in the following form.

[0026] 2FACl + 2TEA → AKD + 2TEA·HCl.

[0027] It has been surprisingly found in the present invention that by first pre-adding a first portion of the total TEA to the HEEL-containing reaction system to obtain a HEEL-containing reaction system pre-added with TEA, and then adding the remaining second portion of the total TEA and FACl to the HEEL-containing reaction system pre-added with TEA for reaction, the viscosity of the reaction system can be significantly reduced, allowing for the solvent-free (such as toluene) preparation of AKD. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shows the viscosities of the reaction systems of Examples 1-4.

[0029] Figure 2 Shows the viscosities of the reaction systems of Examples 6-8. DETAILED DESCRIPTION

[0030] In some embodiments of the present invention, the present invention provides a method for preparing a sizing agent, comprising the following steps:

[0031] (1) Pre-adding a first portion of the total TEA to the HEEL-containing reaction system to obtain a HEEL-containing reaction system pre-added with TEA; and,

[0032] (2) Adding the remaining second portion of the total TEA and FACl to the HEEL-containing reaction system pre-added with TEA for reaction;

[0033] Wherein the weight percentage of the first portion in the total TEA is not greater than 90% of the total TEA. The weight percentage of the first portion of TEA in the total TEA is: 100% × the ratio of the weight of the first portion of TEA to the sum of the weight of the first portion of TEA and the weight of the remaining second portion of TEA.

[0034] In one aspect of the present invention, the HEEL-containing reaction system of the present invention contains any raw material / intermediate / product involved in the production of the sizing agent, such as FA, TEA, FACl, alkyl ketene, AKD, TEA·HCl, or a combination thereof. In a preferred embodiment, the HEEL-containing reaction system of the present invention contains FACl, TEA, AKD, TEA·HCl, or a combination thereof.

[0035] In one embodiment, the HEEL described herein refers to any mixture containing AKD and TEA·HCl. Optionally, the HEEL further contains TEA or other components. The HEEL described herein can be either fresh or recycled. In one embodiment, the HEEL described herein is a part of the reaction mixture for producing the sizing agent in an earlier batch, which includes AKD and TEA·HCl, preferably also including unreacted TEA.

[0036] In one embodiment, the AKD and TEA·HCl in the HEEL can be present in any ratio. In one embodiment, the weight ratio of the AKD and TEA·HCl is from 1:1 to 10:1, preferably from 3:1 to 6:1.

[0037] In another embodiment, the AKD, TEA·HCl and TEA (if present) in the HEEL can be present in any ratio. In still another embodiment, the weight ratio of the AKD, TEA·HCl and TEA (if present) is from 1:1:5 to 10:1:1, preferably from 3:1:1 to 6:1:1.

[0038] In one aspect of the present invention, the reaction mixture of the present invention comprises FA, TEA, FACl, alkyl ketene, AKD, TEA·HCl, or a combination thereof. In one embodiment, the reaction mixture of the present invention refers to the mixture of the reaction (2FACl + 2TEA → AKD + 2TEA·HCl).

[0039] In one embodiment, the HEEL-containing reaction system described herein further comprises FA, TEA, FACl, alkyl ketene, AKD, TEA·HCl, or a combination thereof in addition to HEEL. In another embodiment, the HEEL-containing reaction system described herein does not contain other components in addition to HEEL.

[0040] Any raw material described herein, such as FA, TEA, FACl, alkyl ketene, AKD and / or TEA·HCl, can be either fresh or recycled.

[0041] In one embodiment, the fatty acyl chloride (FACl) described herein is a compound having the structural formula (II):

[0042]

[0043] wherein,

[0044] The R' group, each time it appears, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbon group; and / or

[0045] The R'' group, each time it appears, is independently selected from: hydrogen; an optionally substituted, straight-chain or branched C1-C 30 hydrocarbon group.

[0046] For either R' or R'', the C1-C 30 hydrocarbon group is preferably a C 10 -C 20 hydrocarbon group, more preferably a C 13 -C 17Hydrocarbyl, such as C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 、C 11 、C 12 、C 13 、C 14 、C 15 、C 16 、C 17 、C 18 、C 19 、C 20 、C 21 、C 22 、C 23 、C 24 、C 25 、C 26 、C 27 、C 28 、C 29 、C 30 hydrocarbyl. For either R' or R", the hydrocarbyl may be an alkyl, alkenyl, or alkynyl; preferably an alkyl.

[0047] In one aspect of the present invention, the fatty acyl chloride (FACl) described herein may be a mixture of two or more fatty acyl chlorides. Similarly, the AKD described herein may be a mixture of two or more AKDs. The fatty acids described herein may be a mixture of two or more fatty acids. The fatty acyl chlorides, fatty acids, and AKDs described herein may have the same or different hydrocarbyl moieties.

[0048] In one aspect of the present invention, the addition (preferably simultaneous addition) of FACl and the second portion of TEA occurs between 50 °C and 70 °C, such as 51 °C, 52 °C, 53 °C, 54 °C, 55 °C, 56 °C, 57 °C, 58 °C, 59 °C, 60 °C, 61 °C, 62 °C, 63 °C, 64 °C, 65 °C, 66 °C, 67 °C, 68 °C, 69 °C, 70 °C; preferably, it occurs between 52 °C and 68 °C; more preferably it occurs between 52 °C and 65 °C.

[0049] In one aspect of the present invention, the weight percentage of the first part in the total TEA is not more than 90% of the total TEA, for example, between greater than 0% and 90%, such as 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80%, 79%, 78%, 77%, 76%, 75%, 74%, 73%, 72%, 71%, 70%, 69%, 68%, 67%, 66%, 65%, 64%, 63%, 62%, 61%, 60%, 59%, 58%, 57%, 56%, 55%, 54%, 53%, 52%, 51%, 50%, 49%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, 40%, 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%; or between any two of the above values, preferably between 10% and 90%.

[0050] In a preferred embodiment, the addition (preferably simultaneous addition) of FACl and the second part of TEA occurs between 52°C and 68°C.

[0051] In one aspect of the present invention, the weight percentage of the first part in the total TEA is between 10% and 90% of the total TEA. In a preferred embodiment, the addition (preferably simultaneous addition) of FACl and the second part of TEA in step (2) occurs between 52°C and 68°C, more preferably between 52°C and 65°C.

[0052] In one aspect of the present invention, FACl and / or the second part of TEA are added at the same or different rates in step (2). In some embodiments, the rate of addition of FACl is from 5 ml / min to 20 ml / min, preferably the rate is from 6 ml / min to 16 ml / min. In some embodiments, the rate of addition of TEA is from 1 ml / min to 10 ml / min, preferably the rate is from 4 ml / min to 8 ml / min.

[0053] In one aspect of the present invention, during the reaction process, the viscosity of the reaction system is less than 250 cp, less than 240 cp, less than 230 cp, less than 220 cp, less than 210 cp, less than 200 cp, less than 190 cp, less than 180 cp, less than 170 cp, less than 160 cp, less than 150 cp, less than 140 cp, less than 130 cp, less than 120 cp, less than 110 cp, less than 100 cp, less than 90 cp.

[0054] In one aspect of the present invention, when the reaction process stops, the viscosity of the reaction system is less than 250 cp, less than 240 cp, less than 230 cp, less than 220 cp, less than 210 cp, less than 200 cp, less than 190 cp, less than 180 cp, less than 170 cp, less than 160 cp, less than 150 cp, less than 140 cp, less than 130 cp, less than 120 cp, less than 110 cp, less than 100 cp, less than 90 cp.

[0055] In one aspect of the present invention, the ratio of the total molar amount of the first part of TEA and the second part of TEA to the molar amount of FACl is from 0.95:1 to 2:1, preferably from 1.4:1 to 1.75:1. In one aspect of the present invention, the ratio of the total weight of the first part of TEA and the second part of TEA to the weight of FACl is from 1:3 to 2:3, preferably from 1:1.7 to 1:2.1.

[0056] The method of the present invention can reduce the viscosity of the reaction mixture. The reduced viscosity of the reaction mixture reduces the energy consumption required for stirring. At the same time, the reduced viscosity of the reaction mixture also enables the production of sizing agents (such as AKD) under conditions / operations without solvents such as toluene.

[0057] In one aspect of the present invention, the present invention relates to a method for preparing a sizing agent under toluene-free conditions, comprising the following steps:

[0058] (1) Pre-adding the first part of TEA of the total TEA to the HEEL-containing reaction system to obtain a HEEL-containing reaction system pre-added with TEA; and,

[0059] (2) Adding the remaining second part of TEA of the total TEA and FACl to the HEEL-containing reaction system pre-added with TEA to carry out the reaction;

[0060] Wherein the weight percentage of the first part in the total TEA is not more than 90% of the total TEA.

[0061] In one aspect of the present invention, the present invention relates to a method for reducing the viscosity in the preparation process of a sizing agent (such as reducing the viscosity of the reaction mixture), comprising the following steps:

[0062] (1) Add a first portion of total TEA to the HEEL-containing reaction system to obtain a TEA-preadded HEEL-containing reaction system; and,

[0063] (2) Add the remaining second portion of total TEA and FACl to the TEA-preadded HEEL-containing reaction system to effect a reaction;

[0064] wherein the weight percentage of the first portion in the total TEA is not more than 90% of the total TEA.

[0065] As used herein, the term "substituted" means that any one or more hydrogens on the specified atom or group are replaced by a moiety selected from the indicated groups, provided that the normal valence of the specified atom is not exceeded.

[0066] "Alkyl" is a branched or straight-chain saturated aliphatic hydrocarbon group. In one embodiment, the alkyl contains 1 to about 20 carbon atoms, more typically 1 to about 12 carbon atoms, 1 to about 6 carbon atoms or 1 to about 4 carbon atoms. In one embodiment, the alkyl contains 1 to about 8 carbon atoms. In certain embodiments, the alkyl is C1-C2, C1-C3 or C1-C6. As used herein, the specified range refers to each member of the range as an independent species of alkyl group. For example, as used herein, the term C1-C 30 alkyl refers to straight-chain or branched-chain alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 carbon atoms and is intended to refer to each of these as an independent species description. For example, as used herein, the term C1-C4 alkyl refers to straight-chain or branched-chain alkyl groups having 1, 2, 3 or 4 carbon atoms and is intended to refer to each of these as an independent species description. When C0-C n alkyl is used in combination with another group herein, such as (C3-C7 cycloalkyl)C0-C4 alkyl or -C0-C4 alkyl(C3-C7 cycloalkyl), the indicated group - in this case cycloalkyl, is directly bonded via a single covalent bond (C0 alkyl) or connected via an alkyl chain (in this case 1, 2, 3 or 4 carbon atoms). Alkyl can also be connected via other groups such as heteroatoms, as in -O-C0-C4 alkyl(C3-C7 cycloalkyl). Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl and 2,3-dimethylbutyl. In one embodiment, the alkyl group is optionally substituted as described above.

[0067] "Alkenyl" is a branched or straight-chain aliphatic hydrocarbon group having one or more carbon-carbon double bonds, where the double bonds can occur at stable points along the chain. Non-limiting examples are C2-C8 alkenyl, C2-C6 alkenyl, and C2-C4 alkenyl. As used herein, a specified range refers to each member of the range as an independent species of alkenyl group, as described above for the alkyl moiety. For example, as used herein, the term C1-C 30 alkenyl refers to straight-chain or branched alkenyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 carbon atoms and is intended to refer to each of these as an independent species description. Examples of alkenyl include, but are not limited to, vinyl and propenyl. In one embodiment, the alkenyl group is optionally substituted as described above.

[0068] "Alkynyl" is a branched or straight-chain aliphatic hydrocarbon group having one or more carbon-carbon triple bonds, where the triple bonds can occur at any stable point along the chain, such as C2-C8 alkynyl or C2-C6 alkynyl. As used herein, a specified range refers to each member of the range as an independent species of alkynyl group, as described above for the alkyl moiety. For example, as used herein, the term C1-C 30 alkynyl refers to straight-chain or branched alkynyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 carbon atoms and is intended to refer to each of these as an independent species description. Examples of alkynyl include, but are not limited to, ethynyl, propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, and 5-hexynyl. In one embodiment, the alkynyl group is optionally substituted as described above.

[0069] "Hydrocarbyl" is a branched or straight-chain saturated, unsaturated aliphatic group. The hydrocarbyl can be an alkyl, alkenyl, or alkynyl. As used herein, a specified range refers to each member of the range as an independent group. For example, as used herein, the term C1-C 30 hydrocarbyl refers to hydrocarbyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 carbon atoms and is intended to refer to each of these as an independent species description.

[0070] The temperature described in this text refers to degrees Celsius. As needed, the concentration / content / dosage / parts described in this text can be the concentration / content / dosage / parts expressed in weight, volume, mole, weight / volume, or volume / weight.

[0071] The addition described in this text refers to addition by any means. The second parts of TEA and FACl described in this text can be added simultaneously or not simultaneously. The second parts of TEA and FACl described in this text can be added at the same rate or at different rates.

[0072] In this text, the sum of the first part of TEA and the (remaining) second part of TEA can be referred to as the total TEA. Similarly, the sum of the weight of the first part of TEA and the weight of the (remaining) second part of TEA can be called the total TEA weight.

[0073] The total TEA described in this text refers to the total amount of TEA to be used, such as the total amount of TEA to be used calculated based on FACl. Compared with FACl, the amount can be less than, equal to, or in excess of the amount. Those skilled in the art can determine a reasonable total amount of TEA because the reaction of preparing AKD by reacting TEA with FACl is a reaction known in the art. Generally, those skilled in the art use weight as the unit for feeding and monitoring in this reaction because this reaction is not actually carried out in a stoichiometric manner.

[0074] In this text, the weight percentage of the first part of TEA is 100% × the ratio of the weight of the first part of TEA to the sum of the weight of the first part of TEA and the weight of the remaining second part of TEA, and can be referred to as the X value or X range.

[0075] For example, in the present invention, HEEL can be used in an amount of about 5 wt% to 40 wt% of the amount of the reaction mixture for producing the sizing agent in an earlier batch, preferably between 5 wt% and 20 wt%. In one embodiment, the amount of HEEL accounts for 5 wt% to 40 wt% of the total reaction system.

[0076] The method described in this text can be carried out in a continuous manner or an intermittent manner, preferably in an intermittent manner.

[0077] In this text, the terms "reaction mixture" and "reaction system" can be used interchangeably.

[0078] In this text, the term "the first part of TEA" refers to the part of TEA that is intended to be pre-added to the reaction system containing HEEL.

[0079] Now, the technical solutions of the present invention will be described in combination with specific examples. It should be understood that the following examples are only used to illustrate the present invention and not to limit the scope of the present invention. Unless otherwise specified, the reagents described in this example are all commercially available.

[0080] Specific example

[0081] Example 1 (control group): Without the first part of TEA

[0082] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 40.6 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 60:40 (wt%), Kemira, FennoWax1840TF) into the reactor, start stirring, heat to melting, then add 10.8 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Co., Ltd.). After mixing evenly, start dropping 405 g of acyl chloride (n-C16 acyl chloride:n-C18 acyl chloride = 60:40 (wt%), Kemira) at a rate of 13.8 ml / min, and at the same time drop 219 g of triethylamine at a rate of 6.8 ml / min. Keep the temperature of the system at 60 - 62 °C during dropping. After dropping, keep the temperature at 60 °C for 1 hour. The viscosity of the reaction system during the whole reaction process is monitored by a Emerson online viscometer ( Figure 1 ), and the final viscosity of the system is 973 cP. After separation, a light yellow AKD product is obtained, with a purity higher than 85% (meeting the implementation standard: GB / T 27565 - 2011).

[0083] Example 2: The weight ratio of the first part of TEA in TEA is 70%

[0084] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 40.6 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 60:40 (wt%), Kemira, FennoWax1840TF) into the reactor, start stirring, heat to melting, then add 10.8 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Co., Ltd.) and 153 g of triethylamine (analytical grade, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, start dropping 400 g of acyl chloride, (n-C16 acyl chloride:n-C18 acyl chloride = 60:40 (wt%), Kemira) at a rate of 14.2 ml / min, and at the same time drop 66 g of triethylamine at a rate of 5.2 ml / min. Keep the temperature of the system at 60 - 62 °C during dropping. After dropping, keep the temperature at 60 °C for 1 hour. The viscosity of the reaction system during the whole reaction process is monitored by a Emerson online viscometer ( Figure 1 ), and the final viscosity of the system is 155.1 cP. After separation, a light yellow AKD product is obtained, with a purity higher than 85% (meeting the implementation standard: GB / T 27565 - 2011).

[0085] Example 3: The weight ratio of the first part of TEA in the total TEA is 6.4%

[0086] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 40.6 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 60:40 (wt%), Kemira, FennoWax1840TF) into the reactor. Start stirring and heat to melting. Then add 10.8 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Co., Ltd.) and 14 g of triethylamine (analytical pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, start dropping 400 g of acyl chloride (n-C16 acyl chloride:n-C18 acyl chloride = 60:40 (wt%), Kemira) and 205 g of triethylamine. Keep the temperature of the system at 60 - 62 °C during dropping. After dropping, keep the temperature at 60 °C for 1 hour. The viscosity of the reaction system during the whole reaction process is monitored by a Rosemount on-line viscometer ( Figure 1 ). The final viscosity of the system is 228.3 cP. A light yellow AKD product is obtained by separation, and the purity is higher than 85% (meeting the implementation standard: GB / T 27565 - 2011).

[0087] Example 4 (control group): The weight ratio of the first part of TEA to the total TEA is 100%

[0088] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 40.6 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 60:40 (wt%), Kemira, FennoWax1840TF) into the reactor. Start stirring and heat to melting. Then add 10.8 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Co., Ltd.) and 219 g of triethylamine (analytical pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, start dropping 400 g of acyl chloride (n-C16 acyl chloride:n-C18 acyl chloride = 60:40 (wt%), Kemira). Keep the temperature of the system at 60 - 62 °C during dropping. After dropping, keep the temperature at 60 °C for 1 hour. The viscosity of the reaction system during the whole reaction process is monitored by a Rosemount on-line viscometer ( Figure 1 ). The final viscosity of the system is 715 cP. A light yellow AKD product is obtained by separation, and the purity is higher than 85% (meeting the implementation standard: GB / T 27565 - 2011).

[0089] Example 5: The weight ratio of the first part of TEA to the total TEA (146.1 g) is 1.4%

[0090] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 40.6 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 5:95 (wt%), Kemira, FennoWax1895TFE) into the reactor. Start stirring and heat to melting. Then add 10.8 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Technology Co., Ltd.) and 2.1 g of triethylamine (analytical grade, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, lower the system temperature to about 58 °C. The mixture solidifies and stirring becomes difficult, and the reaction cannot proceed at this temperature. Example 6: The weight ratio of the first part of TEA to the total TEA is 21%

[0091] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 69.4 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 5:95 (wt%), Kemira, FennoWax1895TFE) into the reactor. Start stirring and heat to melting. Then add 35.3 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Technology Co., Ltd.) and 30.8 g of triethylamine (analytical grade, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, start to drip 405 g of acyl chloride (n-C16 acyl chloride:n-C18 acyl chloride = 5:95 (wt%), Kemira) and 115.3 g of triethylamine, and keep the system temperature at 58 - 60 °C during the dripping process. After the dripping is completed, keep the temperature at 63 °C for half an hour. The whole reaction process is monitored by a Rosemount online viscometer for the viscosity of the reaction system ( Figure 2 ), and the final viscosity of the system is 106.6 cP. After separation, a light yellow AKD product is obtained, with a purity higher than 88% (meeting the implementation standard: GB / T 27565 - 2011).

[0092] Example 7: The weight ratio of the first part of TEA to the total TEA is 21%

[0093] Before feeding, evacuate and replace the reactor with nitrogen 2 - 3 times. Charge 69.4 g of AKD wax powder (n-C16 alkyl AKD:n-C18 alkyl AKD = 5:95 (wt%), Kemira, FennoWax1895TFE) into the reactor. Start stirring and heat to melting. Then add 35.3 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Technology Co., Ltd.) and 30.8 g of triethylamine (analytical grade, Shanghai Lingfeng Chemical Reagent Co., Ltd.). After mixing evenly, start to drip 405 g of acyl chloride (n-C16 acyl chloride:n-C18 acyl chloride = 5:95 (wt%), Kemira) and 115.3 g of triethylamine, and keep the system temperature at 62 - 64 °C during the dripping process. After the dripping is completed, keep the temperature at 63 °C for half an hour. The whole reaction process is monitored by a Rosemount online viscometer for the viscosity of the reaction system ( Figure 2), the final viscosity of the system is 120.5 cP. A light yellow AKD product is obtained by separation, and the purity is higher than 88% (meeting the implementation standard: GB / T 27565-2011).

[0094] Example 8 (control group): The weight ratio of the first part of TEA to the total TEA is 100%

[0095] Before feeding, the reactor is evacuated and replaced with nitrogen 2-3 times. 69.4 g of AKD wax powder (n-C16 alkyl AKD: n-C18 alkyl AKD = 5:95 (wt%), Kemira, FennoWax1895TFE) is put into the reactor. Stirring is started and heated to melting. Then 35.3 g of triethylamine hydrochloride (99%, Shanghai Macklin Biochemical Technology Co., Ltd.) and 146.1 g of triethylamine (analytical pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.) are added. After mixing evenly, 405 g of acyl chloride (n-C16 acyl chloride: n-C18 acyl chloride = 5:95 (wt%), Kemira) is started to be dropped. The temperature of the system is maintained at 62-64 degrees during dropping. After dropping, it is kept warm at 63 degrees for half an hour. The viscosity of the reaction system is monitored by a Rosemount online viscometer during the whole reaction process ( Figure 2 ), the final viscosity of the system is 262.8 cP. A light yellow AKD product is obtained by separation, and the purity is higher than 88% (meeting the implementation standard: GB / T 27565-2011).

[0096] The mechanism described in the specification of this application is only for explaining the present invention and is not intended to limit the present invention in any way.

[0097] The descriptions of the foregoing examples and embodiments should be regarded as illustrative rather than limiting the invention described herein. The above specific embodiments are only specific solutions of the present invention, and the protection scope of the present invention includes but is not limited to the solutions of the above specific embodiments. Any embodiment that conforms to the scope described in the present invention and any appropriate changes or modifications made by those of ordinary skill in the art in the technical field to which it belongs shall fall within the protection scope of the present invention.

[0098] As used herein, the terms "approximate", "about", "substantially" and similar terms are intended to have a broad meaning that is generally consistent and accepted by those skilled in the art of the subject matter of this disclosure. Those skilled in the art who read this disclosure should understand that these terms are intended to describe certain features and are not intended to limit these features to the precise numerical ranges provided. Therefore, these terms should be interpreted as indicating that non-substantive or insignificant modifications or variations of the subject matter described and claimed are considered to be within the scope of the present invention as set forth in the appended claims.

[0099] As used herein, terms such as "optional" or "optionally" are intended to indicate that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. Unless otherwise specified, the indefinite articles "a" or "an" and their corresponding definite article "the" as used herein mean at least one, or one or more.

Claims

1. A method for preparing a sizing agent, comprising the following steps: (1) Pre-add a first portion of the total TEA to the HEEL-containing reaction system to obtain a HEEL-containing reaction system with pre-added TEA; And, (2) Add the remaining second portion of the total TEA and FACl to the HEEL-containing reaction system with pre-added TEA to carry out a reaction; Wherein the weight percentage of the first portion in the total TEA is not more than 90% of the total TEA.

2. The method according to claim 1, wherein in step (2), the addition of the second portion of TEA and FACl is carried out between 50°C and 70°C, preferably between 52°C and 68°C.

3. The method according to claim 1 or 2, wherein the weight percentage of the first portion in the total TEA is between 10% and 90% of the total TEA.

4. The method according to any one of the preceding claims, wherein in step (2), the addition of the second portion of TEA and FACl is carried out between 52°C and 68°C, and the weight percentage of the first portion in the total TEA is 10% to 90% of the total TEA.

5. The method according to any one of the preceding claims, wherein in step (2), FACl and the second portion of TEA are added at the same or different rates.

6. The method according to claim 5, wherein the rate of adding FACl is 5 ml / min to 20 ml / min, preferably the rate is 6 ml / min to 16 ml / min.

7. The method according to claim 5, wherein the rate of adding the second portion of TEA is 1 ml / min to 10 ml / min, preferably the rate is 4 ml / min to 8 ml / min.

8. The method according to any one of the preceding claims, wherein the ratio of the total weight of the first portion of TEA and the second portion of TEA to the weight of FACl is 1:3 to 2:3, preferably 1:1.7 to 1:2.

1.

9. The method according to any one of the preceding claims, wherein, The HEEL-containing reaction system contains, in addition to HEEL, FA, TEA, FACl, alkyl ketene, AKD, TEA·HCl, or a combination thereof.

10. The method according to any one of the preceding claims, wherein the sizing agent is alkyl ketene dimer (AKD).

11. The method according to any one of the preceding claims, wherein during the reaction process, the viscosity of the reaction system is less than 250 cp, preferably less than 200 cp, more preferably less than 150 cp, and most preferably less than 100 cp.

12. The method according to any one of the preceding claims, wherein when the reaction process stops, the viscosity of the reaction system is less than 250 cp, preferably less than 200 cp, more preferably less than 150 cp, and most preferably less than 100 cp.

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